1. Field of the Invention
The present invention generally relates to support devices. More specifically, the present invention is drawn to a mechanical device for raising and lowering the landing gear on a semi-trailer.
2. Description of the Related Art
Usually, a semi-trailer is loaded and unloaded in free-standing position (unattached to the cab). Landing gear must be lowered to support the semi-trailer in this free-standing position and raised when the trailer is reattached to the cab. In most instances the landing gear is raised and lowered by manipulating a hand crank. Hand cranking requires that the operator bend over to rotate the crank. This scenario increases the potential for back strain and requires an inordinate amount of repetitive muscular exertion. Bending or stooping to manually turn the landing gear crank is the second highest cause of injury, lost work time and worker's compensation expense for truck drivers.
Ergonomics is the science of fitting the physical demands of the job to the worker to reduce or eliminate repetitive motion injuries that can lead to such disorders as tendonitis, repetitive stress syndrome and back problems. According to the National Academy Of Science, there are more than one million such injuries annually. A manual cranking apparatus, which apparatus would reduce the potential for muscular-skeletal injury and provide for more efficient torquing would certainly be a welcome addition to the art.
There is a plethora of devices in the related art for raising and lowering landing gear sans hand cranks. For example, U.S. Pat. No. 4,466,637 (Nelson), U.S. Pat. No. 6,224,103 B1 (Hatcher) and U.S. Pat. No. 6,260,882 (Kingsbury) employ electric motors to raise and lower the landing gear.
U.S. Pat. No. 4,402,526 (Huetsch), U.S. Pat. No. 5,451,076 (Burkhead) and U.S. Pat. No. 5,911,437 (Lawrence) utilize pneumatic actuators, while U.S. Pat. No. 4,928,488 (Hunger) provides a hydraulic actuator to raise and lower the landing gear.
All of the systems disclosed in the above-cited references require a substantial amount of refitting to existing trailers, which refitting would entail a large expense. Furthermore, all the systems are relatively complicated and would require relatively extensive and costly maintenance.
None of the above inventions and patents, taken either singularly or in combination, is seen to disclose a folding, ergonomic cranking apparatus for raising and lowering landing gear as will subsequently be described and claimed in the instant invention.